Several proposed and adopted transmission applications require high bandwidth. Examples include 155 Mbit/s ATM-1 and 125 Mbit/s FDDI. Arthess transmission rates, the generation of electromagnetic interference (EMI) at physical interfaces, for example connectors and from the transmission cable become problematic. This problem is of increasing concern as regulatory agencies draft and impose rules limiting the level of allowable emission. Because of EMI problems, shielded coaxial cable has been the traditional medium for high-speed rates of single-ended transmission and shielded twisted pair cable has been the traditional medium for high-speed rates of differential transmission. EMI radiation is suppressed by using a very high performance balun and a high performance common-mode choke to achieve balanced differential transmission. However, at rates greater than 100 Mbit/s, baluns may not be sufficiently balanced to suppress the generation of EMI, may be too bulky to be installed on printed circuit boards, or may not have sufficient bandwidth.